Certified Rhythm Analysis Technician (CRAT) Practice Exam

The presence of a "Wenckebach" rhythm, also known as Mobitz Type I or first-degree heart block, is characterized by a progressive prolongation of the PR interval on the electrocardiogram (ECG) until a QRS complex is dropped. This pattern indicates a form of atrioventricular (AV) block where the conduction time through the AV node progressively increases with each beat until the impulse fails to conduct to the ventricles, resulting in a dropped beat.

This phenomenon occurs because the AV node is experiencing a transient slowing of conduction, which is most commonly seen in benign cases but can also be indicative of underlying heart conditions. The distinctive pattern—a gradual lengthening of the PR interval followed by a non-conducted QRS—makes it easily recognizable to clinicians when analyzing an ECG strip.

In contrast, the other choices describe different arrhythmias or conduction patterns that do not match the progressive nature of the Wenckebach rhythm. For example, consistently prolonged PR intervals without dropped beats would suggest a different form of block (such as Mobitz Type II), and a sustained rapid heart rate without P waves indicates a more chaotic arrhythmia, like atrial fibrillation or junctional rhythms. Regular P waves followed